Ophir is exploring the region in partnership with BG the former exploration arm of British Gas. It is the fourth gas find for the partnership and the biggest in Ophir’s history.

The discovery at the Jodari-1 well has an estimated 3.4 trillion cubic feet of recoverable gas — more than 150% of the 2.2 trillion originally estimated.

Nick Cooper, chief executive of Ophir, said: “These results are important for the future development of Tanzanian offshore industry and for the Ophir-BG partnership.” He described it as a “very strong start” for the five-well drilling campaign in the area.

BG shares also rose on the news, gaining 15.5p — 1% — to 1507p.

BG owns 60% of the partnership with Ophir in Jodari-1, which is 1150 metres underwater.